Well, it's just a start, the most (in)famous policy adopted by people who called themselves Keynesian, even got it written into law if I remember correctly, tha

Well, it's just a start, the most (in)famous policy adopted by people who called themselves Keynesian, even got it written into law if I remember correctly, that failed so badly no one can deny the failure. And let's be careful with No True Keynesian arguments.... Plus, unless I'm grossly misinformed, Keynes theories went a lot further than that claimed insight about aggregate demand and deflation, but I haven't studied him deeply, since when I last looked in the '80s it seemed to be garbage, and nothing I've heard since then changes the opinion I formed.